Exploring bugs and bioenergy: Gina Lewin’s path to the Currie Lab

For many college students, summer provides a chance to test-drive future career paths. When Gina Lewin took advantage of such an opportunity, her test drive hit the jackpot.

In the summer of 2009, Lewin participated in a National Science Foundation-funded program called Research Experience for Undergraduates (REU), which invites college juniors and seniors to join research projects around the country.

At the Great Lakes Bioenergy Research Center (GLBRC) at the University of Wisconsin–Madison, Lewin worked in the lab of chemical and biological engineering professor Brian Pfleger. She was tasked with coaxing a bacterium to produce diesel fuel compounds.

As summer progressed, Lewin’s interest in bioenergy and microbiology grew, but she also found herself falling in love with the big research campus of UW–Madison and the city that surrounds it.

“The REU was my first time doing microbiology research,” Lewin says. “I had been thinking about going to graduate school since the end of my freshman year, but being here definitely cemented that interest.”

Lewin, the daughter of two lawyers, grew up in a semi-rural part of central New Jersey. One of her favorite childhood memories is attending summer nature camps at a nearby environmental education center where she learned to identify the bugs she caught in the woods and streams.

After graduating from high school in 2006, Lewin moved across the country to Pomona College, some thirty miles east of Los Angeles, where she was drawn to science and majored in molecular biology.

But it was not until her REU at UW–Madison that Lewin discovered a connection between her childhood interest in bugs and bioenergy research.

In the lab of GLBRC researcher Cameron Currie, Lewin now studies how insects use microbes to break down cellulose, the sugars found in the cell walls of woody plants, in order to procure nutrient-enriched food. Understanding the insects’ process for breaking down cellulose could ultimately inform GLBRC’s own efforts to convert biomass to ethanol and other biofuels.

Lewin’s particular focus is on the insects’ powerful ability to partner with a community of microbes.

“Scientists have long studied how a single microbe in a flask degrades cellulose,” Lewin says. “But in the environment, organisms don’t exist in isolation; they have evolved to be part of a community. Our goal is to apply the power of these symbiotic relationships to biofuel production.”

Leaf-cutter ants found in tropical rainforests are a particularly impressive example of these mutually beneficial relationships.

Living as a highly organized society in colonies that can grow large enough to be visible from space, the vast majority of leaf-cutter ants work to support their queen. In return, the queen maintains the colony by laying up to 20,000 eggs a day for up to twenty years in the lab.

What is perhaps most remarkable, however, is that the leaf-cutter ants are miniature farmers who have perfected their agricultural activities — deconstructing biomass and cultivating a fungus — over the course of ten million years. Humans, in contrast, have spent a mere 12,000 years developing and fine-tuning their agricultural expertise.

Leaf-cutter ants collect and degrade large amounts of fresh leaves that the fungus converts to food.

“The fungus makes a fuzzy pearl-like structure that contains the nutrients the ants need,” Lewin says. “The larvae and the queen only eat these fungal structures, while the adult workers also feed on leaf sap and fruits.” Some species of leaf-cutter ants even grow a bacterium on their body that protects the fungus from pathogens.

Each colony’s fungus farm consists of a garden, where the plant material is first deposited and partially degraded, and a dump, a dedicated waste management site that may be located under- or aboveground, depending on the ant species.

“Seventy percent of the leaves’ cellulose is carried to the dump for final degradation. It turns out that the dump’s microbial community is much more efficient at degrading cellulose than any individual strain we have studied thus far,” Lewin summarizes her dissertation findings.

Currie, Lewin’s advisor, is as pleased with these results as with Lewin’s success in obtaining external funding for her work.

“I teased Gina that the offer letter for the National Science Foundation’s predoctoral fellowship [dated around April 1, 2012] was probably an April Fool’s joke,” Currie recalls. “These fellowships are incredibly competitive. I’ve never even heard of anyone getting one in their second year.”

Graduate school clearly suits Lewin well, whether she peers through the microscope, gathers fungal samples in Costa Rica, or applies for a research fellowship.

“In college, I had to choose between ecology and molecular biology,” Lewin remembers. “When I decided to major in molecular biology, I was a little sad to leave behind the outdoor activities we did in the ecology classes. But graduate school has allowed me to bring those two interests back together.”

Last but not least, Lewin has also contributed significantly to GLBRC’s education and outreach efforts.

In the summer of 2011, Lewin worked with high school science teacher Craig Kohn from Waterford, Wis., who participated in GLBRC’s Research Experience for Teachers (RET) program. Together they designed a classroom activity that adapted Lewin’s lab assay for demonstrating the breakdown of cellulose for a high school level.

“We figured out that Craig could make a cheap growth medium for microbes by mixing Miracle Gro fertilizer from a garden center with tap water,” Lewin explains.

To see if an environmental sample, such as a scoop of cow manure, contains microbes capable of growing on a piece of cellulosic filter paper, Kohn’s high school students put the sample, the paper, and the fertilizer in a test tube. The students then quantified cellulose degradation by counting the days until a complete tear was observed in the paper.

The following two summers, Lewin and John Greenler, director of GLBRC’s education and outreach program, presented the activity to teachers attending the Bioenergy Institute for Educators. And in the fall of 2014, the activity was expanded for UW–Madison freshmen and used in a First-Year Interest Group (FIG) course in bioenergy.

“In today’s world, just being a great researcher and doing teaching assistant duty for one semester is no longer enough to become a successful faculty member. Gina is a poster child for the importance of translating her research into engaging classroom material,” Greenler says.

“In the six years since her REU, Gina has grown into a real spokesperson for GLBRC,” Greenler adds.

The GLBRC is one of three Department of Energy Bioenergy Research Centers created to make transformational breakthroughs and build the foundation of new cellulosic biofuels technology. For more information on the GLBRC, visit www.glbrc.org.